Studies of the specificity and efficiency of reactions catalyzed by enzymes and the elucidation of a biological control mechanism are the particular subjects of this proposal. The enzymes chosen are of interest to health-related problems. The serine proteases include enzymes involved in blood clotting, nerve transmission, and digestive processes. A serine protease, acetylcholinesterase, and acetylcholine receptor protein, are major components in nerve and muscle function.